In the chemical industry one of the important ways of purifying materials is by crystallization. This process consists of super-saturating a solvent and effecting crystallization by cooling or evaporating additional solvent to form a slurry of desired crystals and mother liquor. Usually, the slurry is removed from a crystallization vessel, the mother liquor is separated by filtration or by centrifugation. The separated crystals are washed and then the purified product is recovered. This process requires repeated solids handling, in addition to multiple and varied pieces of equipment that need maintenance and attention. It would be desirable to carry out all the steps in one unit.
Some batch-type chemical reactions are carried out in liquid phase using a heterogeneous catalyst. In other instances the catalyzed reactions start as homogeneously catalyzed systems, but at completion of the reaction the catalyst is crystallized from the liquid, because its solubility in the product of the reaction is lower than the solubility in the starting ingredients. The catalyst is not spent and is reusable. However, for such catalytic reactions in the past, it has been necessary to drain a reactor, separate the solid catalyst from the liquid phase, wash and recover the catalyst and reload the reactor with the catalyst to repeat the reaction. Avoiding the necessity of removing the solid catalyst from and reloading to the reactor before repeating the reaction results in a much more efficient procedure than that of prior art operations.